The invention relates to facsimile systems and, more particularly, to a facsimile system having the function of storing image data.
Along with the increasing popularity of facsimile systems among various users in recent years grow the needs for new facsimile systems with more sophisticated functions. To meet such needs, a facsimile system having an image memory for storing image data (hereinafter abbreviated as the "memory FAX") has been developed.
In the memory FAX received image data is not printed out immediately, but the image data is temporarily stored in an image memory and printed out at a desired timing afterwards. As to image data to be transmitted which is read with a scanner, the read image data is not transmitted immediately, but temporarily stored in the image memory and transmitted at a predetermined timing afterwards. Such a technique allows communication time to be reduced compared with conventional systems, which thus provides the user with the advantage curtailing communication fees.
Also, the memory FAX has a so-called "substituted receive" function, in which image data can be received storing the received image data in the image memory even after a recording sheet has run out. The substitute receive thus ensures reception of image data even if a recording sheet has been used up.
The thus designed memory FAX, however, addresses various problems arisen from memory capacity restrictions. To overcome the problems, the following proposals have heretofore been made.
(1) When image data for memory transmission has been stored in the image memory and then there is a reception immediately before transmitting that stored image data, the received data is outputted on a realtime basis if the recording sheet is ready, and the image data stored in the memory is transmitted upon end of the reception. However, if the recording sheet is insufficient or has run out during the reception, the memory, being occupied by the image data for transmission, cannot therefore ensure substitute reception. PA1 (2) As in item (1), once the storage capacity of the image memory becomes insufficient due to the storage of image data for memory transmission or the storage of a large volume of image data received as substitute receptions, substitute reception can no longer be executed.
To overcome the above problem, proposed in, e.g., Japanese Patent Unexamined Publication No. 31563/1990 is a technique, in which when data is received in the form of substitute reception with image data for memory transmission already stored, a memory area for the substitute reception is reserved by deleting the image data for memory transmission.
To overcome the above problem, proposed in e.g., Japanese Patent Unexamined Publication No. 171060/1990 is a technique, in which image data is transferred to pre-registered destinations upon reception of the image data with the remaining storage capacity of the image memory scarce.
As facsimile communications become popular, direct mails or erroneous facsimile communications increase, which annoys the users with the reception of unnecessary data.
However, as represented by the above-mentioned conventional art, no prioritization in terms of importance or emergency has been made on the received data and thus all the received data are treated equally. Therefore, unnecessary image data or image data of low importance have been received in the form of substitute reception without any restriction, leaving necessary image data out from the image memory.
The invention has been made in view of the above circumstances. Accordingly, an object of the invention is to utilize an image memory efficiently by allowing only necessary image data to be stored selectively or preferentially.